Physics, 10.03.2020 07:46 mahkitheking16

Suppose the dam is 80% efficient at converting the water's potential energy to electrical energy. How many kilograms of water must pass through the turbines each second to generate 45.0 MWMW of electricity? This is a typical value for a small hydroelectric dam.

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Answer from: personm21

This question involves the concepts of efficiency, potential energy, and electrical energy.

"2.2 x 10⁵ kg/s" of water must pass through the turbines each second, assuming a waterfall height of 26 m.

First, we will use the formula for the efficiency of conversion from potential energy to electrical energy.

$Efficiency=\frac{electrical\ power}{potential\ energy/t}\\\\\frac{potential\ energy}{t} = \frac{electrical\ energy}{efficiency}\\\\\frac{mgh}{t}=\frac{45\ MW}{0.8}\\\\\frac{mgh}{t}=56.28\ MW=56.28\ x\ 10^6\ W$

assuming h = 26 m:

$\frac{m}{t}=\frac{56.28\ x\ 10^6\ W}{(9.81\ m/s^2)(26\ m)}\\\\\frac{m}{t}=2.2\ x\ 10^5\ kg/s$

Learn more about efficiency here:

link

The attached picture shows the pyramid representing energy efficiency.

Answer from: zaniyastubbs9

$\dot m = 163877.114\,\frac{kg}{s}$

Explanation:

Let assume that the water dam has a fall of 35 meters. The required instantaneous potential energy is:

$\dot E_{g} = \frac{\dot E_{el}}{\mu_{el}}$

$\dot E_{g}= \frac{45\times 10^{6}\,W}{0.8}$

$\dot E_{g} = 56.25\cdot 10^{6}\,W$

The instantaneous potential energy has the following model:

$\dot E_{g} = \dot m \cdot g \cdot \Delta h$

The mass flow rate needed to produced the required energy production:

$\dot m = \frac{56.25\times 10^{6}\,W}{(9.807\,\frac{m}{s^{2}} )\cdot (35\,m)}$

$\dot m = 163877.114\,\frac{kg}{s}$

Suppose the dam is 80% efficient at converting the water's potential energy to electrical energy. Ho

Answer from: Quest

It won't lose or gain electrons if it's a covalent bond it shares the electrons with another atom or atoms. if it is an ionic bond it will lose the 3 electrons on the outer shell and become a positively charged ion. credit goes to @sunshinebaby of answers.yahoo.com.

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

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